U.S. patent application number 10/597745 was filed with the patent office on 2007-11-29 for piston device for internal combustion engine.
This patent application is currently assigned to KABUSHIKI KAISHA RIKEN. Invention is credited to Naoki Iijima, Takeshi Yamada, Hideki Yoshida.
Application Number | 20070272078 10/597745 |
Document ID | / |
Family ID | 34857679 |
Filed Date | 2007-11-29 |
United States Patent
Application |
20070272078 |
Kind Code |
A1 |
Yamada; Takeshi ; et
al. |
November 29, 2007 |
Piston Device for Internal Combustion Engine
Abstract
A top ring has gas seal and oil control functions realizing
approximately the same amount of oil consumption and blow-by gas as
realized by three rings. A piston assembly includes a piston body
having a top land portion and a ring groove on its periphery, and a
piston ring having a U-shaped cross section including upper and
lower leg portions and a base portion connecting the leg portions,
and attached to the top land portion. Axial length from boundary of
the base portion of the piston ring and the upper leg portion to a
lower surface of the lower leg portion is larger than that from an
upper surface of the top land portion to lower surface of the ring
groove fitting the lower leg portion. Alternatively, axial grooves
are on a thrust side of the top land portion, or a V-shaped annular
groove is in a second land portion.
Inventors: |
Yamada; Takeshi;
(Kashiwazaki-shi, JP) ; Yoshida; Hideki;
(Kashiwazaki-shi, JP) ; Iijima; Naoki;
(Kashiwazaki-shi, JP) |
Correspondence
Address: |
BLACKWELL SANDERS LLP
720 OLIVE STREET
SUITE 2400
ST. LOUIS
MO
63101
US
|
Assignee: |
KABUSHIKI KAISHA RIKEN
13-5, Kudankita 1-chome Chiyoda-ku
Tokyo
JP
|
Family ID: |
34857679 |
Appl. No.: |
10/597745 |
Filed: |
January 21, 2005 |
PCT Filed: |
January 21, 2005 |
PCT NO: |
PCT/US05/02041 |
371 Date: |
August 4, 2006 |
Current U.S.
Class: |
92/208 ;
123/193.6 |
Current CPC
Class: |
F16J 15/326 20130101;
F02F 3/00 20130101; F16J 9/20 20130101 |
Class at
Publication: |
092/208 ;
123/193.6 |
International
Class: |
F16J 1/04 20060101
F16J001/04; F02F 3/00 20060101 F02F003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 12, 2004 |
JP |
2004-035357 |
Claims
1. A piston assembly for an internal-combustion engine comprising:
a piston body including a top land portion and a ring groove formed
on its periphery; and a piston ring having a U-shaped cross
section, the piston ring including an upper leg portion, a lower
leg portion, and a base portion connecting the upper and lower leg
portions, the piston ring being attached to the top land portion of
the piston body, wherein an axial length from a boundary of the
base portion of the piston ring and the upper leg portion to a
lower surface of the lower leg portion is set to be larger than an
axial length from an upper surface of the top land portion of the
piston body to a lower surface of the ring groove into which the
lower leg portion of the piston ring is fitted.
2. A piston assembly for an internal-combustion engine comprising:
a piston body including a top land portion and a ring groove formed
on its periphery; and a piston ring having a U-shaped cross
section, the piston ring including an upper leg portion, a lower
leg portion, and a base portion connecting the upper and lower leg
portions, the piston ring being attached to the top land portion of
the piston body, wherein at least one axial groove is provided on a
thrust side of the top land portion of the piston body.
3. A piston assembly for an internal-combustion engine comprising:
a piston body including a top land portion and a ring groove formed
on its periphery; and a piston ring having a U-shaped cross
section, the piston ring including an upper leg portion, a lower
leg portion, and a base portion connecting the upper and lower leg
portions, the piston ring being attached to the top land portion of
the piston body, wherein the piston body further includes a second
land portion in which a V-shaped annular groove is formed.
4. The piston assembly for an internal-combustion engine according
to claim 1, wherein the piston ring has an upper periphery of a BF
(barrel face) shape and a lower periphery formed as a straight or
tapered contact face.
5. The piston assembly for an internal-combustion engine according
to claim 2, wherein the piston ring has an upper periphery of a BF
(barrel face) shape and a lower periphery formed as a straight or
tapered contact face.
6. The piston assembly for an internal-combustion engine according
to claim 3, wherein the piston ring has an upper periphery of a BF
(barrel face) shape and a lower periphery formed as a straight or
tapered contact face.
Description
TECHNICAL FIELD
[0001] The present invention relates to a shape of a piston in an
internal-combustion engine in which the piston is reciprocated, and
a shape of a piston ring.
BACKGROUND ART
[0002] In an internal-combustion engine in which a piston is
reciprocated, a set of three rings is usually used for each
cylinder, which includes two compression rings and one oil
ring.
[0003] Those three rings share a gas seal function and an oil
control function. That is, the top ring and the second ring carry
out the gas seal function, and the second ring and the oil ring
carry out the oil control function. In this manner, required
functions of a piston ring are carried out by a set of three
rings.
[0004] In recent years, the internal-combustion engines have
problems of increase of engine revolutions, increase of an engine
output, and reduction of friction. Those problems can be
effectively solved by reducing the number of the rings.
[0005] Therefore, a piston assembly using a single piston ring is
conventionally proposed (see Patent document 1, for example). A
piston assembly for internal-combustion engine is also known in
which a compression piston ring having a square U-shaped cross
section is fitted to a top land portion of a piston body in order
to improve a seal function and the like (see Patent document
2).
[0006] Patent document 1: Japanese Utility-Model Application
Publication No. 58-24558
[0007] Patent document 2: Japanese Utility-Model Application
Publication No. 5-42661
DISCLOSURE OF INVENTION
[0008] Problems to be Solved by the Invention
[0009] However, in a case of a single piston ring as described in
Patent document 1, it is not possible to sufficiently carry out
both the functions of gas seal and oil control.
[0010] In addition, the piston assembly described in Patent
document 2 is designed in such a manner that a crown face of the
piston body firmly comes into contact with an upper leg portion of
the compression piston ring having a square U-shaped cross section
when a compression pressure acts. Thus, entrance of compressed gas
into back clearance is prevented, and the piston ring cannot
sufficiently conform to the cylinder. Therefore, the gas seal
function and the oil control function cannot be carried out
sufficiently.
[0011] The present invention was made in order to overcome the
aforementioned problems of the conventional piston assemblies. It
is an object of the present invention to provide a piston assembly
for internal-combustion engine, which includes a TOP-ring that can
have superb functions of gas seal and oil control.
[0012] Means to Solve the Problem
[0013] According to the present invention, a piston assembly for
internal-combustion engine includes: a piston body including a top
land portion and a ring groove formed on its periphery; and a
piston ring having a U-shaped (or square U-shaped) cross section.
The piston ring includes an upper leg portion, a lower leg portion,
and a base portion connecting the upper and lower leg portions. The
piston ring is attached to the top land portion of the piston body.
An axial length from a boundary of the base portion of the piston
ring and the upper leg portion to a lower surface of the lower leg
portion is set to be larger than an axial length from an upper
surface of the top land portion of the piston body to a lower
surface of the ring groove into which the lower leg portion of the
piston ring is fitted.
[0014] According to the present invention, a piston assembly for
internal-combustion engine includes: a piston body including a top
land portion and a ring groove formed on its periphery; and a
piston ring having a U-shaped (or square U-shaped) cross section.
The piston ring includes an upper leg portion, a lower leg portion,
and a base portion connecting the upper and lower leg portions. The
piston ring is attached to the top land portion of the piston body.
At least one axial (or vertical) groove is provided on a thrust
side of the top land portion of the piston body.
[0015] In addition, according to the present invention, a piston
assembly for internal-combustion engine includes: a piston body
including a top land portion and a ring groove formed on its
periphery; and a piston ring having a U-shaped (or square U-shaped)
cross section. The piston ring includes an upper leg portion, a
lower leg portion, and a base portion connecting the upper and
lower leg portions. The piston ring is attached to the top land
portion of the piston body. The piston body further includes a
second land portion in which a V-shaped annular groove is
formed.
[0016] According to a fourth aspect of the invention as set forth
in claim 4, the piston ring in the piston assembly for
internal-combustion engine according to any one of the first to
third aspects has an upper periphery of a BF (barrel face) shape
and a lower periphery formed as a straight or tapered contact
face.
[0017] Effect of the Invention
[0018] According to the present invention, a single piston ring can
have superb functions of gas seal and oil control. Thus, the number
of piston rings can be reduced. Thereby, the increase of engine
revolutions of an internal-combustion engine, the increase of the
engine output, and the reduction of friction can be also
achieved.
[0019] In addition, according to the present invention, it is
possible to actively allow the heat in an upper part of the piston
to escape toward a cylinder, thus improving the wear resistance of
the ring groove of the piston body.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a perspective view of a piston assembly 1 for an
internal-combustion engine according to an embodiment of the
present invention;
[0021] FIG. 2 is an enlarged view of a main part in FIG. 1;
[0022] FIG. 3 is a schematic top plan view of an engine to which
the piston assembly 1 shown in FIG. 1 is applied;
[0023] FIG. 4 is a graph showing results of comparison of the
piston assembly 1 shown in FIG. 1 with a conventional piston
assembly with respect to the amount of oil consumption;
[0024] FIG. 5 is an enlarged view of a main part of a piston
assembly 1A for internal-combustion engine according to another
embodiment of the present invention;
[0025] FIG. 6 is an enlarged view of a main part of a piston
assembly 1B for internal-combustion engine according to another
embodiment of the present invention; and
[0026] FIG. 7 is an enlarged view of a main part of a piston
assembly 1C for internal-combustion engine according to another
embodiment of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0027] The invention will now be described based on the preferred
embodiments shown in the drawings.
[0028] FIGS. 1 to 3 show a piston assembly 1 for an
internal-combustion engine according to an embodiment of the
present invention (which corresponds to claims 1 to 3).
[0029] The piston assembly 1 of the present embodiment includes a
piston body 10 and a piston ring 20. The piston body 10 has a top
land portion 12 and a ring groove 13 formed on its periphery. The
piston ring 20 is attached to the top land portion 12 of the piston
body 10. The piston ring 20 has a U-shaped cross section and
includes an upper leg portion 22, a lower leg portion 23, and a
base portion 21 connecting the upper and lower leg portions 22 and
23. An axial length h2 from a boundary P of the base portion 21 of
the piston ring 20 and the upper leg portion 22 to a lower surface
23a of the lower leg portion 23 is set to be larger than an axial
length h3 from an upper surface 12b of the top land portion 12 to a
lower surface 13a of the ring groove 13 to which the lower leg
portion 23 of the piston ring 20 is attached. In other words, the
sum of an axial length h4 of the base portion 21 of the piston ring
20 and an axial length h5 of the lower leg portion 23 is set to be
larger than the sum of an axial length h6 of the top land portion
12 of the piston body 10 and an axial length h7 of the ring groove
13. When a compression pressure acts in this arrangement, the lower
surface 23a of the lower leg portion 23 of the piston ring 20
firmly comes into contact with the lower surface 13a of the ring
groove 13 and clearance is generated around the entire internal
surface of the piston ring 20 having a U-shaped cross section.
Entering of compressed gas into this clearance pushes the piston
ring 20 and the piston ring 20 conforms to the cylinder, thereby
improving the sealing property. A value of h2-h3 is preferably
40.+-.20 .mu.m in a case of a gasoline engine and 100.+-.20 .mu.m
in a case of a diesel engine. It is preferable to set tolerance to
fall within the above range.
[0030] FIGS. 1 and 2 show the arrangement in which a notch 25 is
formed in a crown face 11 of the piston body 10 and the upper leg
portion 22 of the piston ring 20 is fitted into the notch 25.
However, the present invention is not limited to this arrangement.
For example, the present invention can be also applied to an
arrangement in which the piston body 10 does not have the notch 25
and the upper leg portion 22 of the piston ring 20 is attached to
project upward from the crown face 11 of the piston body 10. In
this case, the same effects can be achieved by setting the axial
length h2 from the boundary P of the base portion 21 of the piston
ring 20 and the upper leg portion 22 to the lower surface 23a of
the lower leg portion 23 to be larger than the axial length h3 from
the upper surface (i.e., the crown face 11 in this case) of the top
land portion 12 to the lower surface 13a of the ring groove 13 to
which the lower leg portion 23 is attached.
[0031] It is preferable that axial grooves 14 be provided on a
thrust side of the top land portion 12 of the piston body 10. In
the example of FIG. 3, the axial grooves 14 are arranged on the
thrust side at positions of 80-degree, 90-degree, and 100-degree
from a front position 31 of an engine 30. The axial grooves 14 are
formed to extend from the crown face 11 of the piston body 10 to
the periphery 12a of the top land portion 12 along the upper side
of the top land portion 12. The engine 30 communicates with a
transmission 32, as shown in FIG. 3. The leading-end side of the
engine 30 is called as a front side, and the rear-end side is
called as a rear side. The positions of the axial grooves 14 are
not limited, as long as they are arranged on the thrust side (in a
range from 0 to 180-degree from the front position 31). It is
preferable that the axial grooves 14 be arranged in a range from 45
to 135-degree.
[0032] The formation of those axial grooves can increase a pressure
on the back of the piston ring 20, thus improving the oil control
function and the seal function. This arrangement can be applied not
only to the aforementioned piston assembly in which the lower
surface 23a of the lower leg portion 23 of the piston ring 20
having a U-shaped cross section firmly comes into contact with the
lower surface 13a of the ring groove 13 of the piston body 10 when
a compression pressure acts, but also to a piston assembly in which
the crown face (or upper surface of the top land) of the piston
body firmly comes into contact with the upper leg portion of the
piston ring having a U-shaped cross section when a compression
pressure acts, like the conventional piston assembly. This
arrangement can achieve excellent effects in both the piston
assemblies.
[0033] It is preferable to form a V-shaped annular groove 15 in a
second land portion 16 of the piston body 10. The annular groove 15
can ease up the increase of the oil pressure on the second land
portion 16. Thus, leak of oil into a combustion chamber through the
top land portion 12, which increases oil consumption, can be
prevented. Please note that the upper surface of the V-shaped
groove described here is horizontal or inclined in such a manner
that its inner circumferential portion is elevated. In addition,
the V-shaped groove described here has a radial width that becomes
smaller downward in its lower part. It is preferable that an angle
of the lower surface of the V-shaped groove with respect to the
piston axis be in a range of 15 to 45-degree. The annular groove 15
may have a square U-shaped, a U-shaped, or a reversed V-shaped
cross section, instead of the aforementioned V-shape. However, in a
case of the V-shape annular groove 15, it is easy to collect oil
into the annular groove and therefore a beneficial effect of
reducing oil consumption can be achieved.
[0034] That V-shaped annular groove can be applied not only to the
aforementioned piston assembly in which the lower surface 23a of
the lower leg portion 23 of the piston ring 20 having a U-shaped
cross section firmly comes into contact with the lower surface 13a
of the ring groove 13 when a compression pressure acts, but also to
a piston assembly in which the crown face (or upper surface of the
top land) of the piston body firmly comes into contact with the
upper leg portion of the piston ring having a U-shaped cross
section when a compression pressure acts, like the conventional
piston assembly. In both the piston assemblies, the V-shaped
annular groove can achieve excellent effects.
[0035] During a expansion stroke, the piston body 10 moves down on
the thrust side. In order to effectively scrape oil from the second
land portion 16 by using a side pressure of the piston body 10
during the expansion stroke, it is preferable that t1 (the distance
between the top land portion 12 and the second land portion 16) be
approximately equal to t2 (the thickness of the piston ring) in
FIG. 2. It is also preferable to set a value of t1-t2 to 0 to 50
.mu.m.
[0036] An operation of the piston assembly 1 for
internal-combustion engine according to the present embodiment,
that has the aforementioned arrangement, is now described.
[0037] In the present embodiment, the piston ring 20 having a
U-shaped cross section is attached to the piston body 10 in such a
manner that the lower surface 23a of the lower leg portion 23 can
slide on the lower surface 13a of the ring groove 13. Thus, when a
compression pressure acts on the piston body 10, the lower surface
23a of the lower leg portion 23 of the piston ring 20 slides on the
lower surface 13a of the ring groove 13 so as to stretch the piston
ring 20 outward. As a result, a space S is formed between the inner
circumferential surface 21 a of the base portion 21 of the piston
ring 20 and the periphery 12a of the top land portion 12. A space
is formed between the entire inner circumferential surface of the
piston ring 20 and the piston body 10. The space S has a labyrinth
effect, and makes it difficult to transfer oil that moves from the
second land portion 16 to the back of the piston ring 20 via the
lower side face of the piston ring 20, to the combustion chamber.
Therefore, the effect of reducing oil consumption can be
achieved.
[0038] Even in a case of using a low-tension piston ring, the
piston ring 20 is conformed to the cylinder C when a gas pressure
acts. Thus, the piston ring 20 can carry out the gas seal
function.
[0039] In the present embodiment, the axial grooves 14 for
increasing the backpressure on the piston ring 20 are provided on
the thrust side of the top land portion 12 of the piston body
10.
[0040] The axial grooves 14 are arranged at positions of 80-degree,
90-degree, and 100-degree from the front position 31 of the engine
30. Therefore, during an expansion stroke on the thrust side where
the oil film thickness while the engine actually works is thick,
the back pressure on the piston ring 20 on the thrust side is
increased via the grooves 14 with the increase of the pressure in
the cylinder (combustion pressure), thus effectively reducing the
oil film thickness. In this manner, the excellent oil control
function can be carried out.
[0041] In the present embodiment, the piston ring 20 is attached to
the top land portion 12 that is located at an upper end of the
piston body 10. Thus, the temperature at the crown face 11 and the
top land portion 12 of the piston body 10 can be reduced.
[0042] Experiments of the piston assembly 1 for an
internal-combustion engine according to the present embodiment were
conducted while comparing the piston assembly with a conventional
single-ring.
[0043] A naturally-aspirated 1.8-liter gasoline engine having a
bore of 79 mm was used in the experiments.
[0044] The piston ring 20 used in the experiments had a U-shaped
cross section and were made of steel. The dimension of t2 was 0.5
mm. The dimension of h1 was 2.0 mm and the dimension of a1 was 2.0
mm.
[0045] The following three piston bodies were manufactured. The
above piston ring 20 was attached to each of those piston bodies so
as to obtain piston assemblies of Examples 1, 2 and 3.
[0046] The piston assembly of Example 1 included a piston body
having the following arrangement. A notch into which the upper leg
portion of the piston ring having a U-shaped cross section was
fitted was formed in the crown face of the piston body. A ring
groove into which the lower leg portion of the piston ring was
fitted was provided below the crown face.
[0047] The dimensions of the notch and the ring groove in the axial
direction were set to be larger than the dimensions of the upper
leg portion and the lower leg portion of the piston ring in the
axial direction by about 50 .mu.m, respectively. The dimensions of
the notch and the ring groove in the radial direction were set to
be larger than the dimension a1 of the piston ring by about 50
.mu.m.
[0048] 2) The piston assembly of Example 2 included a piston body
having the following arranngement. Three axial grooves were
provided on the thrust side of the piston body 10 of piston
assembly of Example 1. The three axial grooves were arranged at
positions of 80-degree, 90-degree, and 100-degree from the front
position. Each axial groove extended from the crown face to the
periphery of the top land portion and had a width of 3 mm and a
depth of 5 mm.
[0049] 3) The piston assembly of Example 3 included a piston body
having the following arrangement. Three axial grooves were provided
on the thrust side of the piston body of the piston assembly of
Example 1 in a similar manner to those of Example 2. In addition, a
V-shaped annular groove was formed in the second land portion of
the piston body.
[0050] Moreover, the amount of oil consumption and blow-by gas were
measured in a piston with a single compression ring. The result of
this measurement is shown as a conventional single-ring set in FIG.
4. This piston had no V-shaped annular groove in the second land
portion of the piston body.
[0051] As shown in FIG. 4, it was confirmed that the amount of oil
consumption was reduced in the piston assembly of Example 1 that
employed the piston ring having a U-shaped cross section according
to the present invention, as compared with the conventional
single-ring set. Here, the amount of blow-by gas was also reduced
in the piston assembly of Example 1 as compared with the
conventional single-ring set. The amount of oil consumption was
further reduced by providing the grooves on the thrust side of the
piston body. The amount of oil consumption was significantly
reduced by further providing the V-shaped annular groove on the
piston body (Example 3). The amount of blow-by gas was reduced from
14.0 L/min in the conventional single-ring set to 12.2 L/min in the
piston assembly of Example 3.
[0052] FIG. 5 shows a piston assembly 1A for internal-combustion
engine according to another embodiment of the present
invention.
[0053] The piston assembly 1A of the present embodiment is
different from the piston assembly 1 of the above embodiment in the
following points. Upper and lower surfaces 12b, 12c of the top land
portion 12 are tapered. That is, the top land portion 12 is formed
to have a reversed keystone shape. A lower surface 22a of the upper
leg portion of the piston ring 20 having a U-shaped cross section
and an upper surface 23b of the lower leg portion are tapered in
such a manner that the width of each leg portion in the axial
direction becomes larger toward the periphery of the piston
assembly.
[0054] The piston assembly 1A of the present embodiment is
advantageous in that carbons interposed between the piston ring 20
and the top land portion 12 can be easily discharged.
[0055] In this case, it is preferable that the axial length h2 from
the boundary P of the base portion 21 of the piston ring 20 and the
upper leg portion 22 to the lower surface 23a of the lower leg
portion be set to be larger than the axial length h3 from an
periphery upper end A of the top land portion 12 to the lower
surface 13a of the ring groove 13 into which the lower leg portion
of the piston ring is fitted. Moreover, it is preferable that an
axial length h10 from an inner circumferential lower end Q of the
upper leg portion of the piston ring 20 to the lower surface 23a of
the lower leg portion be set to be larger than an axial length h11
from an inner circumferential upper end B of the top land portion
12 to the lower surface 13a of the ring groove 13. In this
arrangement, the lower surface 23a of the lower leg portion 23
moves outward on the lower surface 13a of the ring groove 13 when a
compression pressure acts on the piston body 10. Thus, a space is
formed between the entire inner circumferential surface of the
piston ring 20 and the periphery of the top land portion 12. This
space has a labyrinth effect, and makes it difficult to transfer
oil that moves from the second land portion 16 to the back of the
piston ring 20 via the lower side face of the piston ring 20, to
the combustion chamber. Thus, the effect of reducing oil
consumption can be achieved.
[0056] The piston assembly 1A of the present embodiment operates in
the same manner as that of the above embodiment and has the same
effects as those achieved in the above embodiment.
[0057] FIG. 6 shows a piston assembly 1B for internal-combustion
engine according to still another embodiment of the present
invention.
[0058] The piston assembly 1B is different from the above piston
assemblies 1 and 1A of the above embodiments in the following
points. An upper periphery 24 of the piston ring 20 has a BF
(barrel face) shape and projects outward by about 0.5 mm. A lower
periphery 25 of the piston ring 20 is formed as a tapered contact
face that projects outward by about 0.5 mm. In the present
embodiment, the piston ring 20 hardly comes into contact with the
cylinder at an edge because the upper periphery 24 of the piston
ring 20 has a barrel face shape. Thus, the piston assembly 1B of
the present embodiment is effective in preventing scuff.
[0059] The piston assembly 1B also has an advantage that an
excellent effect of scraping oil can be achieved during a
moving-down stroke of the piston body 10, because the lower
periphery 25 is formed as a tapered contact face.
[0060] In the piston assembly 1B, a single piston ring has
different shapes in the upper part and the lower part. Thus, as
compared with the piston ring 20 shown in FIG. 2, the effective
contact area can be made smaller and a face pressure under the same
tension can be increased. When the face pressure is large, the
following capability of the periphery of the piston ring is better
and the oil consumption is improved.
[0061] Alternatively, the lower periphery 25 may be formed as a
straight contact face.
[0062] The piston assembly 1B of the present embodiment operates in
the same manner as those of the above embodiments and can achieve
the same effects as those achieved in the above embodiments.
[0063] FIG. 7 shows a piston assembly 1C for internal-combustion
engine according to further another embodiment of the present
invention.
[0064] The piston assembly 1C is different from the piston
assemblies 1, 1A, and 1B of the above embodiments in that both the
upper periphery 24 and the lower periphery 25 of the piston ring 20
are formed as contact faces of a half-barrel shape.
[0065] The piston assembly 1C can also achieve the same effects as
those achieved by the piston assembly 1B of the embodiment of FIG.
6.
[0066] The piston assembly 1C operates in the same manner as those
of the piston assemblies of the above embodiments.
* * * * *